Scientists are increasingly concerned that Greenland’s thawing ice sheet could contribute to rising sea levels faster than has already been projected. Warmer temperatures may be leading to more algae, darkening the surface of the ice and causing it absorb more solar radiation, warming, and therefore melting, more rapidly. As the largest mass of ice in the northern hemisphere, if it were to melt entirely Greenland would raise average sea levels around the world by about 7 meters, or 20 feet.

A five-year UK research project called Black and Bloom is investigating these species of algae and how they could spread, to create more accurate projects of future rises in sea level.

Increases due to this algae was not included in the UN climate panel’s projections of sea level rise, in its most recent report in 2013. According to that report, a rise 98 centimeters by the end of the century was the worst case scenario.

Scientists are now working on the ice sheet to measure the amount of solar radiation reflected by the surface. White snow reflects as much as 90 percent of solar radiation, while patches of dark algae reflect just 35 percent, or even as little as 1 percent in the darkest areas.

According Bristol University Professor Martyn Tranter:

“People are very worried about the possibility that the ice sheet might be melting faster and faster in the future. We suspect that in a warming climate these dark algae will grow over larger and larger parts of the Greenland ice sheet and it might well be that they will cause more melting and an acceleration of sea level rise.

“Our project is trying to understand just how much melting might occur.”

In the last two decades, Greenland has reached a tipping point, losing more ice than it gains back in winter from snowfall, a disruption in a balance that once kept the ice sheet stable.

Dr. Joe Cook, a glacial microbiologist at Sheffield University said of the algae:

“We know they’re very widespread and we know that they’re very dark and we know that that’s accelerating melt but that’s not something that’s built into any of our climate projections – and that’s something that needs to change.”

“When we say the ice sheet is melting faster, no one saying it’s all going to melt in next decade or the next 100 years or even the next 1,000 years but it doesn’t all have to melt for more people to be in danger – only a small amount has to melt to threaten millions in coastal communities around world.”